AGGRESSIVE OLIGODENDROGLIOMAS, tumors that are symptomatic, enlarging, enhancing, and usually but not always anaplastic, respond to chemotherapy. We have observed responses to chemotherapy in 18 of 19 consecutively treated patients with newly diagnosed or recurrent aggressive oligodendrogliomas. A regimen of procarbazine, CCNU (lomustine), and vincristine (PCV) is predictably effective, but other drugs have anti-oligodendroglioma activity. Cooperative group trials will be necessary to determine the most effective drug, or combination of drugs, and to explore fully the role of chemotherapy in the treatment of this uncommon glioma.